MC Version: 1.16.5
C&B Version: chiselsandbits-1.0.12-RELEASE-universal.jar
Do You have Optifine: No

The new menu is only readable in GUI Scale 3, anything smaller and it's no longer readable.
See a comparison of the old vs new radial menu as well as Building Gadget's and the FTB minimap:

The FTB minimap seems to bypass the scaling completely, that may not work but I wanted to give it as example.

C&B 0.x font was 8px, 16px and 24px high (or actually, an 8px font scaled 1x, 2x and 3x). If you look at the font in close-up you can see the character pixels are scaled 2x or 3x:

Maybe start with the smallest (GUI Scale 1) fontsize wise, then allow to scale up? Adding the shadow would help too probably.